Bovine spongiform encephalopathy (BSE) is a world-wide problem for consumers of agriculture, industrial and medical products. An altered form of the prion (PrP) gene appears to be the causative agent, and an endogenous PrP gene is necessary for infection. Advanced Cell Technology and the University of Massachusetts recently announced the birth of three cloned transgenic calves, George, Charlie and Albert. In phase I of this project, we will extend this work, by creating a targeting vector for the bovine prion gene,, PrP, and optimizing the conditions for electroporation and drug selection in bovine embryonic fibroblasts cells. In phase II, we will create BEF cells and cattle containing a homologously-targeted PrP gene. Based on evidence from PrP knockout mice, we hypothesize that are cloned transgenic animals will be unable to both transmit and contract the prion-based disease, BSE. Thus, the long term goal of this project is to create a strain of cattle to be used: (1) to study PrP function in cattle, (2) as a source of prion-free embryonic tissue to treat neurodegenerative disease (3) to increase the safety profile of bovine derived products for research and pharmaceuticals, and (4) as a source of prion-free food products for consumers. PROPOSED COMMERCIAL APPLICATIONS: Cattle containing a targeted deletion of prion protein can be used commercially (1) as a source of prion-free embryonic tissue to treat neurodegenerative disease (2) to increase the safety profile of bovine-derived products (3) as a source of prion-free food products